(a) Field of the Invention
The present invention relates to an engine clutch control system for a hybrid vehicle which controls engagement of an engine clutch, and a method of controlling the engine clutch.
(b) Description of the Related Art
Demand for environmentally-friendly vehicles is increasing, and hybrid vehicles are provided as a practical alternative to vehicles having only a gasoline engine.
Although hybrid vehicles can be distinguished from fuel cell vehicles and electric vehicles in a narrow sense, hybrid vehicles as described herein refer to vehicles equipped with one or more batteries and using the energy stored in the batteries for driving themselves.
Hybrid vehicles typically are equipped with an engine and a motor, which are power sources, and improvement of fuel efficiency and reduction of exhaust gases can be achieved by the characteristics of the engine and the motor which depend on traveling circumstances.
Hybrid vehicles can be provided with an optimal output torque, depending on how the engine and the motor are operated while the vehicles are driven by the two power sources, that is, the engine and the motor.
For hybrid vehicles, a TMED (Transmission Mounted Electric Device) type of power train is generally used, an engine clutch is disposed between the two power sources, the engine and the motor, and they travel in an EV mode or an HEV mode in accordance with engagement (connection) of the engine clutch.
In general, hybrid vehicles determine the engagement timing of the engine clutch and control the engagement (connection) of the engine clutch to reduce shock and satisfy the starting performance when engaging (connecting) the engine clutch while changing into the HEV (Hybrid Electric Vehicle) mode from the EV (Electric Vehicle) mode.
When engaging (connecting) the engine clutch to change into the HEV mode from the EV mode, the ways of engaging the engine clutch are different in accordance with the status and condition of the vehicles.
It is known to require significant testing and effort to satisfy the required performance of a hybrid vehicle, including considering all operating conditions, and the engagement performance of the engine clutch may be changed in accordance with the magnitude and the inclination of the reference speed and the relative speed even under the same speed difference.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.